-LRB- CNN -RRB- -- A fast-moving wildfire in Southern California is threatening homes and has prompted evacuations .

The fire , which was reported Wednesday , jumped from approximately 300 acres to 5,000 acres , according to Capt. Lucas Spelman with the California Department of Forestry and Fire Protection .

Some 450 firefighters are working the blaze , which is located in Riverside County .

Mandatory evacuations are in effect for the communities of Poppet Flats , Twin Pines and Silent Valley , fire officials said .

It was not immediately clear how many people are affected .

An evacuation center was set up at an area high school .

CNN 's Diahann Reyes contributed to this report .

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NEW : The fire is estimated at 5,000 acres , up from 300 earlier

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Some 450 firefighters are working the blaze , located in Riverside County